Screening of Mammalian DNA Polymerase Inhibitors from Rosemary Leaves and Analysis of the Anti-inflammatory and Antiallergic Effects of the Isolated Compounds

In this study, on screening mammalian DNA polymerase (pol) inhibitors from the extracts of 20 edible plants, we found that leaves of rosemary (Rosmarinus officinalis L.) showed the strongest pol inhibition; furthermore, we isolated four components, carnosic acid, carnosol, ursolic acid, and rosmarinic acid, from an extract of the leaves. Carnosic acid inhibited the activities of all 11 mammalian pols tested. In descending order of their inhibitory effect on pol λ, which is a DNA repair/recombination pol, the four compounds ranked as follows: carnosic acid > ursolic acid > carnosol > rosmarinic acid. The inhibition of pol λ by these compounds was significantly correlated with both in vivo anti-inflammatory and antiallergic effects, including on 12-O-tetradecanoylphorbol-13-acetate-induced inflammatory mouse ear edema, and immunoglobulin E-induced passive cutaneous anaphylactic reaction in mice. These results indicate that rosemary and its constituent, carnosic acid, are potential therapeutic food candidates for inflammatory and allergic diseases.